Garth Mountain at Pentyrch just north of Cardiff has a prominent mound on the summit.

Legend claims that this mound was deliberately added by local people in order to make sure that the hill was high enough to be officially classified as a mountain. But historians say the landmark is actually a Bronze Age burial mound.

The myth formed the basis for the film The Englishman who went up a hill and came down a mountainin.

Hugh Grant - currently starring in the hit movie Notting Hill - plays an English map-maker sent to classify the mountains and hills of Wales.

In the film, his plan to class the local summit as a hill is changed when the local people, fearing a loss of status, secretly build an artificial mound to bring the hill up to the official mountain height.

Stream of visitors

The popular movie has resulted in a stream of visitors climbing to the summit of Garth Mountain to view the location.

But the increased number of walkers has caused concerns for conservationists who fear the real treasure of Garth Mountain could be damaged by the myth.

They say the Bronze Age burial chamber has nothing to do with the mountain's classification.

Now the History Society and the local community council are erecting a notice on the mountain to explain its real historical significance.